A multi-valve is generally used for taking turns metering single well production of the well, in order to obtain dynamic well production data. The valve core of the multi-way valve is provided with a valve seat ring, and the sealing surface of the valve seat ring is closely fitted with a sealing surface of the upper valve body. Currently, the sealing surface of the existing valve seat ring is welded/surfacing welded with cemented carbide or cermet, such as what is disclosed in the Chinese patent application ZL200420006528.1, Chinese patent application ZL200620167076.4 and Chinese patent application ZL200920291629.0.
In the normal operation of the multi-way valve, the valve seat ring makes circular motion around a shaft core of the valve core on the sealing surface of the upper valve body, and the sealing pressure ratio of the sealing surface of the valve seat ring to the sealing surface of the upper valve body is mainly provided by a disc spring, therefore, due to the limitations of the elastic force of the disc spring, the existing multi-way valve can only meet the requirement of internal sealing test under low differential-pressure (DP). When the testing differential-pressure (DP) between the gathering and transportation orifice and the metering orifice of a multi-way valve is up to 6.9 MPa, i.e., 1000 psi or even higher, it is far from meeting the leakage requirements of Leakage Level ANSI FCI-70.2 VI by providing the sealing pressure ratio only by the disc spring. Moreover, as for the structure of the traditional valve seat ring, the sealing band on sealing surface thereof is relatively wide, which results in that the force bearing area of the sealing is too large, and the power necessary to attain the sealing pressure ratio required by the sealing of Level VI is large. In this way, as the moment needed to be provided to drive the valve core to rotate becomes larger, especially under the working condition of high pressure, the larger the driving moment is, the larger the shaft diameter of the shaft core needed for transmitting the moment is, which is bad for the structural design of the valve body of the multi-way valve and it needs to select driving electronic assembly with higher power.